Snippets : Unite 2015 - A coder's guide to spline-based procedural geometry

MeshSplinesAndExtrusion.cs

/* Code snippets from Unite 2015 - A coder's guide to spline-based procedural geometry */
/* https://www.youtube.com/watch?v=o9RK6O2kOKo */

// Optimized GetPoint
Vector3 GetPoint( Vector3[] pts, float t ) {
	float omt = 1f-t;
	float omt2 = omt * omt;
	float t2 = t * t;
	return	pts[0] * ( omt2 * omt ) +
			pts[1] * ( 3f * omt2 * t ) +
			pts[2] * ( 3f * omt * t2 ) +
			pts[3] * ( t2 * t );
}

// Get Tangent
Vector3 GetTangent( Vector3[] pts, float t ) {
	float omt = 1f-t;
	float omt2 = omt * omt;
	float t2 = t * t;
Vector3 tangent = 
			pts[0] * ( -omt2 ) +
			pts[1] * ( 3 * omt2 - 2 * omt ) +
			pts[2] * ( -3 * t2 + 2 * t ) +
			pts[3] * ( t2 );
	return tangent.normalized;
}

// Get Normal
Vector3 GetNormal2D( Vector3[] pts, float t ) {
  Vector3 tng = GetTangent( pts, t );
  return new Vector3( -tng.y, tng.x, 0f );
}

Vector3 GetNormal3D( Vector3[] pts, float t, Vector3 up ) {
  Vector3 tng = GetTangent( pts, t );
  Vector3 binormal = Vector3.Cross( up, tng ).normalized;
  return Vector3.Cross( tng, binormal );
}

// Get Orientation
Quaternion GetOrientation2D( Vector3[] pts, float t ) {
Vector3 tng = GetTangent( pts, t );
Vector3 nrm = GetNormal2D( pts, t );
return Quaternion.LookRotation( tng, nrm );
}

Quaternion GetOrientation3D( Vector3[] pts, float t, Vector3 up ) {
  Vector3 tng = GetTangent( pts, t );
  Vector3 nrm = GetNormal3D( pts, t, up );
  return Quaternion.LookRotation( tng, nrm );
}

//

public struct OrientedPoint {

	public Vector3 position;
	public Quaternion rotation;

	public OrientedPoint( Vector3 position, Quaternion rotation ) {
		this.position = position;
		this.rotation = rotation;
	}

	public Vector3 LocalToWorld( Vector3 point ) {
		return position + rotation * point;
	}

	public Vector3 WorldToLocal( Vector3 point ) {
		return Quaternion.Inverse( rotation ) * ( point - position );
	}

	public Vector3 LocalToWorldDirection( Vector3 dir ) {
		return rotation * dir;
	}
}

// 
public void Extrude( Mesh mesh, ExtrudeShape shape, OrientedPoint[] path ){

int vertsInShape = shape.vert2Ds.Length;
int segments = path.Length - 1;
int edgeLoops = path.Length;
int vertCount = vertsInShape * edgeLoops;
int triCount = shape.lines.Length * segments;
int triIndexCount = triCount * 3;
int vertsInShape = shape.vert2Ds.Length;
int segments = path.Length - 1;
int edgeLoops = path.Length;
int vertCount = vertsInShape * edgeLoops;
int triCount = shape.lines.Length * segments;
int triIndexCount = triCount * 3;

int[] triangleIndices 	= new int[ triIndexCount ];
Vector3[] vertices 	= new Vector3[ vertCount ];
Vector3[] normals 		= new Vector3[ vertCount ];
Vector2[] uvs 			= new Vector2[ vertCount ];

/* Generation code goes here */

mesh.Clear();
mesh.vertices = vertices;
mesh.triangles = triangleIndices;
mesh.normals = normals;
mesh.uv = uvs;
/*
foreach oriented point in the path
	foreach vertex in the 2D shape
		Add the vertex position, based on the oriented point
		Add the normal direction, based on the oriented point
		Add the UV. U is based on the shape, V is based on distance along the path
	end
end

foreach segment
	foreach line in the 2D shape
		Add two triangles with vertex indices based on the line indices
	end
end*/

for( int i = 0; i < path.Length; i++ ) {
		int offset = i * vertsInShape;
		for( int j = 0; j < vertsInShape; j++ ) {
			int id = offset + j;
			vertices[id] = path[i].LocalToWorld( shape.vert2Ds[j].point );
			normals[id] = path[i].LocalToWorldDirection( shape.vert2Ds[j].normal );
			uvs[id] = new Vector2( vert2Ds[j].uCoord, i / ((float)edgeLoops) );
		}
	}
	int ti = 0;
	for( int i = 0; i < segments; i++ ) {
		int offset = i * vertsInShape;
		for ( int l = 0; l < lines.Length; l += 2 ) {
			int a = offset + lines[l] + vertsInShape;
			int b = offset + lines[l];
			int c = offset + lines[l+1];
			int d = offset + lines[l+1] + vertsInShape;
			triangleIndices[ti] = a; 	ti++;
			triangleIndices[ti] = b; 	ti++;
			triangleIndices[ti] = c; 	ti++;
			triangleIndices[ti] = c; 	ti++;
			triangleIndices[ti] = d; 	ti++;
			triangleIndices[ti] = a; 	ti++;
		}
	}


// 
void CalcLengthTableInto( float[] arr, CubicBezier3D bezier ) {
	arr[0] = 0f;
	float totalLength = 0f;
	Vector3 prev = bezier.p0;
	for( int i = 1; i < arr.Length; i++ ) {
		float t = ( (float)i ) / ( arr.Length - 1 );
		Vector3 pt = bezier.GetPoint( t );
		float diff = ( prev - pt ).magnitude;
		totalLength += diff;
		arr[i] = totalLength;
		prev = pt;
	}
}

// 
public static class FloatArrayExtensions {
	public static float Sample( this float[] fArr, float t){
		int count = fArr.Length;
		if(count == 0){
			Debug.LogError("Unable to sample array - it has no elements" );
			return 0;
		}
if(count == 1){
			return fArr[0];
		float iFloat = t * (count-1);
		int idLower = Mathf.FloorToInt(iFloat);
		int idUpper = Mathf.FloorToInt(iFloat + 1);
		if( idUpper >= count )
			return fArr[count-1];
		if( idLower < 0 )
			return fArr[0];
		return Mathf.Lerp( fArr[idLower], fArr[idUpper], iFloat - idLower);
	}
}

You get this working? I infer some named classes form the slides like: CubicBezier3D, ExtrudeShape.

The code isn't good as is. There are some mistakes. See examples in the comment section of the video itself.